PLCs or other control devices are used to control automatic machines in factories and the like. Such control devices successively read values from, for example, sensors through their I/O functions and hold the data.
A contemporary control device is connected to a database system and stores its retained data in this database system. This can facilitate the sharing of data among information processing devices connected to the database and the summarization, analysis and the like of various types of data collected. For example, Japanese Unexamined Patent Publication No. 2007-80286 (patent document 1 listed below) discloses a data acquisition device that can transmit I/O data held in a PLC to a host computer in real time.